Method for Producing Rice Haploid by Rice X Maize Hybridization

Abstract

The present invention provides a novel method for producing the rice haploid, i.e., producing the rice haploid by rice×maize hybridization. In this method, rice is used as the female parent, and the rice panicle is emasculated and then pollinated with fresh maize pollens; the emasculated panicle is sprayed with 2, 4-D solution at 50-200 mg/L 24 h after pollination, and after 15-20 days the rice panicle is cut off to collect caryopses; and the haploid embryos are obtained by dissectting caryopses asepticlly, then inoculated and cultured with ½MS medium, then the haploid embryos directly germinate into rice haploid seedlings. Compared with the existing main methods for producing the rice haploid, such as anther culture and isolated microspore culture, the rice haploid production method of the present invention reduces the dependence on rice genotypes, does not produce mixture of haploid and diploid plants, contains no albino seedling, and is simpler in technical operation.

What is claimed is: 
     
         1 . A method for producing the rice haploid by rice×maize hybridization, wherein the rice haploid is produced by the elimination of maize genome in wide cross between rice and maize. 
     
     
         2 . The method for producing the rice haploid by rice×maize hybridization of  claim 1 , comprising the following steps:
 A. emasculation: after heading and before flowering of the rice, for each panicle, cut off the young base spikelets and keep the upper and middle spikelets, and then the panicle is emasculated and bagged after emasculation according to routine methods; 
 B. pollination: the emasculated rice panicle is pollinated with fresh maize pollens when the stigmas of rice florets develop to mature; 
 C. production of haploid embryo: 24 h after the pollination, the pollinated rice panicle is sprayed with 2, 4-dichlorophenoxyacetic acid (2,4-D) solution, and continually grows on the maternal plant; 
 D. cutting of panicle and peeling of caryopsis: the pollinated rice panicle is cut off after growing on the maternal plant for 15-20 days, to collect the caryopses produced through rice×maize hybridization; and 
 E. embryo rescue: dissect the sterilized caryopses on the aseptic bench by stereomicroscope to obtain haploid embryos, and inoculate the haploid embryo into the ½ MS medium, to obtain the rice haploid plant after germination of the haploid embryo. 
 
     
     
         3 . The method for producing the rice haploid by rice×maize hybridization of  claim 2 , wherein in step C, 24 h after the pollinating, the pollinated rice panicle is sprayed with 2,4-D solution at concentration of 50-200 mg/L. 
     
     
         4 . The method for producing the rice haploid by rice×maize hybridization of  claim 3 , wherein in step C the pollinated rice plant is grown in an artificial climate room or an artificial climate chamber under artificial light (about 2 000 lux) 14 hours 27±1° C. or 10 hours 20±1° C. alternately, and keeping 85% humidity. 
     
     
         5 . The method for producing the rice haploid by rice×maize hybridization of  claim 2 , wherein in step D, the pollinated panicle is cut off from the maternal plant when the length of the haploid embryos reach 0.5-1 mm. 
     
     
         6 . The method for producing the rice haploid by rice×maize hybridization of  claim 2 , wherein in step E, the culture medium is ½MS medium, and the haploid embryos are first cultured under dark condition (23±1° C.), then moved to light condition (about 2 000 lux, 23±1° C.) after the haploid embryos germinate into buds, so as to obtain the rice haploid plant.